Studies have suggested the need for individuals to reduce their intake of fat, particularly saturated fat, to minimize the risk of cardiac and other diseases. Moreover, the reduction of overall calories ingested has been of interest to prevent obesity, which has been linked to diabetes, heart disease and other ailments.
In recognition of the need to reduce intake of fat and to decrease the total number of calories consumed, efforts have been undertaken to reduce substantially the amount of fat and the overall calorie count of bread spreads, including those which function to replace butter. For reasons of microbiological stability and resemblance to butter, it is desirable that such spreads be fat-continuous. However, as the amount of fat is decreased below 35%, and particularly below 30%, it becomes increasingly difficult to formulate a stable, fat-continuous spread which is acceptable to consumers. Factors related to consumer acceptance of a spread include the ease of spreading on bread and the similarity to butter of its melting characteristics, both on bread and in the mouth.
Izzo et al. U.S. Pat. No. 4,882,187 discloses a process for preparing an edible spread having a lower fat content than butter or margarine. The process includes admixing with an aqueous composition a plastic dispersion having a continuous fat phase and a discontinuous aqueous phase. The dispersed aqueous phase has a pH above 4.7 and contains proteins whereas the aqueous composition has a pH at or below 4.7, contains hydrocolloid and is substantially free of milk and soy protein. The mixture of the continuous fat phase and the aqueous composition is worked at a temperature at which the fat-continuous phase remains plastic. Izzo et al. discuss the use of either high or low shear.
The Izzo et al. spread is said to include one fat phase and two distinct aqueous phases. The need for emulsifiers is said to be reduced or eliminated. Particularly good results are said to be obtained when butter is used as the fat-continuous plastic dispersion, although it is said that common margarine may be employed. It is said that spreads having as little as 26% fat have been prepared in accordance with the Izzo et al. invention without the assistance of emulsifiers; the preferred range is 30-65% fat. Preferred products are said to be made with butter and gelatin solutions, and in discussing the temperature range of the gelatin solution it is stated that once the gelatin solution has gelled, the resulting product is grainy and has poor organoleptic qualities.
Lissant et al. U.S. Pat. No. 4,844,620 describes a process for preparing a high-internal-phase-ratio emulsion, such as a low fat spread, wherein the external and internal phases have highly disparate viscosities. Lissant et al. feed their phases into a recirculation line which includes a pump, a shearing device, an outlet for removing some of the product for packing and an inlet for recirculating part of the product. The spread of the Lissant et al. example includes emulsifiers, sodium benzoate and citric acid. It is said that the modifying component is dissolved in the external phase. Lissant et al. do not appear to indicate that their aqeuous phase should be gelled.
EP 011,891 indicates that low fat spreads can be improved by including in the continuous fat phase a discontinuous aqueous phase consisting of non-gelled, liquid finely dispersed droplets having a size range from 1 to 5 microns and a second discontinuous aqueous phase consisting of coarse, gelled spherical droplets having a diameter in the range of from 10 to 20 microns. One or both of the aqueous phases may include protein, e.g., milk protein. Emusifiers may also be included.
The '891 publication states that gelling can be effected before, but preferably during, emulsification of the fatty and liquid aqueous ingredients. Also, it is indicated that emulsions can be prepared by using gelled spherical ingredients that have been obtained by emulsifying a liquid gelling agent containing aqueous phase in a fatty phase, letting the gelled spherical ingredients form in situ and by blending the emulsion obtained with another fat-continuous emulsions containing dispersed liquid aqueous phase. In Example 1, two water-in-oil emulsions are mixed in a scraped surface heat exchanger (Votator A unit) at temperatures of 17.degree. C. and 20.degree. C., cooled to 0.degree. C. and packed at 17.degree. C.
Gould et al. U.S. Pat. No. 4,520,037 discloses a fat-continuous emulsion comprising at least two distinct aqueous phases each of which comprises a microbiologically labile nutrient such as milk protein, vegetable protein, glucose, lactose or partially hydrolyzed starch. Antibacterial compounds or preservatives are concentrated in each of the two aqueous phases. The inclusion of emulsifiers is preferred.
Moran GB 1,094,268 discloses a spread for bread comprising a water-in-fat emulsion having 20 to 50% fat wherein the aqueous phase contains a thickening agent and the fat phase includes an emulsifier. One method of preparing the products comprises emulsifying the aqueous phase containing the thickening agent in the partially crystallized fat containing the emulsifier. Prior to mixing, both the aqueous phase and the fatty phase are preferably cooled to temperatures well below the upper melting point of the fat, e.g., between about 25.degree. C. and 45.degree. C. Alginate ester may be used as the thickening agent.
EP 199 397 discloses a process for preparing an edible fat containing product wherein a fat-containing fraction is cooled to cause crystallization of part of the fat and a fraction is mixed with the partially crystallized fraction in a mixer including a pattern of cavities. Protein, gelling and thickening agents are mentioned as possible ingredients. It is said that low fat spreads having a continuous fat phase and a dispersed aqueous phase may be obtained. The amount of crystallized fat is preferably at least 2%. Preferably one fraction comprises at least 80% fat and the other fraction is an aqueous solution or a dispersed system having a continuous aqueous phase. The aqueous phase may contain gelling agents such as gelatin and protein.
In Example 3, of the '397 document, the aqueous phase is a cream which includes milk protein and gelatin.
GB 2 021 140 discloses dairy blends intended to have improved spreadability compared to butter at refrigeration temperatures. The water content can vary from about 10% up to 45% by weight of the total composition. In Example 1, a dairy blend which appears to be approximately 65% fat by weight is prepared by softening butter to 30.degree. C. and mixing therewith a partially gelled solution including gelatin and water. Rape seed oil is then added. In Example 3, milk is used instead of water.
Cain et al. U.S. Pat. No. 4,917,915 discloses spreads containing less than 35 wt. % fat which can be obtained by using a gel-forming aqueous phase having a viscosity of at least 20 mPa.s at 5.degree. C. at a shear rate of 17090 sec.sup.-1.